<!DOCTYPE html>
<html>

	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>

	<body>
		<script>
			var num1 = parseInt(prompt("亲请您输入第一个整数"));
			var num3 = parseInt(prompt("1.+ 2.- 3.* 4./"));
			var num2 = parseInt(prompt("亲请您输入第二个整数"));
			switch(num3) {
				case 1:
					alert(num1 + num2);
					break;
				case 2:
					alert(num1 - num2);
					break;
				case 3:
					alert(num1 * num2);
					break;
				case 4:
					alert(num1 / num2);
				default:
					alert("错误");
					break;
			}
		</script>
	</body>

</html>